Wash. Rev. Code § 2.04.080
The several justices of the supreme court, before entering upon the duties of their office, shall take and subscribe the following oath or affirmation: "I do solemnly swear (or affirm, as the case may be), that I will support the Constitution of the United States and the Constitution of the State of Washington, and that I will faithfully and impartially discharge the duties of the office of judge of the supreme court of the State of Washington to the best of my ability." Which oath or affirmation may be administered by any person authorized to administer oaths, a certificate whereof shall be affixed thereto by the person administering the oath. And the oath or affirmation so certified shall be filed in the office of the secretary of state.
RCW 2.04.080
Oath of judges: State Constitution Art. 4 s 28.